Abstract details

I will present our Evolutionary Synthesis models GALEV that describe both the chemical evolution of the gas and the spectral evolution of the stellar component of various galaxy types, including starbursts and mergers. By using various sets of input physics (stellar evolutionary tracks/isochrones, model atmospheres, yields) for different metallicities, GALEV models allow for a chemically consistent description of galaxies in the sense that they account for the increasing initial metallicities of successive stellar generations. Considering stellar (sub-)populations with subsolar metallicities is already important in describing low-mass and late-type galaxies in the local universe and, of course, even more so for the less chemically evolved galaxies at high redshift. I show differences to previous generations of models and discuss effects on the interpretation of high-redshift galaxies. SFRs, whether derived from emission lines or from rest-frame UV luminosities are significantly overestimated unless subsolar metallicities are appropriately taken into account. In the interpretation of deep multiband imaging data which include the bulk of the intrinsically lower luminosity -- and hence lower metallicity -- galaxy population not accessible to spectroscopy, the inclusion of subsolar metallicity stellar populations is crucial and significantly affects the SFRs, photometric redshifts, spectral types, and photometric masses derived.